This invention relates generally to uninterruptible power supplies for providing backup power to electrical equipment during power outages, and, more specifically, to uninterruptible power supply systems based on metal- or hydrogen-fuel cells.
A great deal of electronic equipment in the modern world relies upon high-quality, reliable electrical power. Such equipment, each a load, includes, for example and without limitation, telecommunications equipment, Internet servers, corporate mail servers, routers, power supplies, computers, test and industrial process control equipment, alarm and security equipment, many other types of electrical devices, equipment for which a power source is necessary or desirable to enable the equipment to function for its intended purpose, and the like, and suitable combinations of any two or more thereof. Over the past decade, as the digital age has taken hold, there has been an explosive growth in the deployment of such equipment.
For many applications of such equipment, power outages can lead to losses of data, equipment damage, missed deadlines, and/or lost productivity, and therefore must be avoided. At the same time, the reliability of the traditional power generation, transmission, and distribution network has fallen in some countries due in part to the increased demands which have been placed on this network throughout the world. The result is that uninterruptible power supplies (UPS) have emerged as a means for providing backup power to such equipment in the event of a power outage.
Traditionally, UPSs use lead-acid batteries as the energy source. Such UPSs typically provide up to about 20 minutes of backup power, which is usually enough time to allow users to shut down their equipment in an orderly fashion, but not enough time to allow the equipment to operate through all power outages. Backup times much longer than this are usually not considered feasible as the required UPSs would be too heavy and bulky.
Even if backup times much beyond 20 minutes were even feasible, another problem that would have to be addressed is the heat generated by the consumption of the backup power by the electrical equipment. In a typical scenario, such heat is generally dissipated into a xe2x80x9ccomputer roomxe2x80x9d or xe2x80x9ccommunications closetxe2x80x9d in which the equipment is housed. Under normal conditions, such areas are typically cooled with an electrical air conditioning system. However, during a power outage, the electrical air conditioning system servicing such areas is typically down. Moreover, backup generators located outside the building and running on diesel fuel, propane, or natural gas are often not feasible for purposes of providing backup power to the air conditioning system because they tend to be expensive, bulky, have adverse environmental impacts, and frequently do not service power outages that occur internal to a building and affect only parts of it.
The invention provides a fuel cell system for providing backup power to one or more loads (including without limitation a cooling unit) upon the occurrence of a power outage condition, defined to include a disruption or discontinuation in the delivery of primary power (i.e., power from a primary source, namely, a source other than the fuel cell system) to the one or more loads. The system comprises one or more fuel cells, each comprising a power source and a fuel storage unit, that deliver backup power to the one or more loads upon the occurrence of a power outage condition. In one aspect, the invention further provides that each fuel cell can optionally further comprise a regeneration unit to regenerate the reactants of the fuel from the reaction products, and/or a reaction product storage unit to store the reaction products from the fuel cell, and/or a second reactant storage unit to store the second reactants. The one or more fuel cells can be metal fuel cells (including without limitation zinc fuel cells, aluminum fuel cells, lithium fuel cells, magnesium fuel cells, iron fuel cells, and the like), hydrogen fuel cells, and/or any other fuel cells that have the same purpose.
In a further embodiment, the fuel cell useful in the practice of the invention system comprises a metal fuel cell. In another aspect, a metal fuel cell system for providing backup power to one or more loads (including without limitation a cooling unit) upon the occurrence of a power outage condition has one, or any suitable combination of two or more, of the following properties: the system can be configured to not utilize or produce significant quantities of flammable fuel or product, respectively; the system can provide backup power to the one or more loads for an amount of time limited only by the amount of fuel present (e.g., in the range(s) from about 0.01 hours to about 10,000 hours or more); the system can be configured to have an energy density in the range(s) of about 35 Watt-hours per kilogram of combined fuel and electrolyte added to about 400 Watt-hours per kilogram of combined fuel and electrolyte added; the system can further comprise an energy requirement, and can be configured such that the combined volume of fuel and electrolyte added to the system is in the range(s) from about 0.0028 L per Watt-hour of the system""s energy requirement to about 0.025 L per Watt-hour of the system""s energy requirement; the system can be configured to have a fuel storage unit that can store fuel at an internal pressure in the range(s) from about xe2x88x925 pounds per square inch (psi) gauge pressure to about 200 psi gauge pressure; the system can be configured to hold a pre-charge of fuel in the power producing cell(s) of the power source of the metal fuel cell, optionally in an amount sufficient to permit operative engagement of the fuel cell(s) at a rate significantly faster than when no such fuel is present and/or sufficient to supply power for a time in the range(s) of about 0.001 minutes to about 100 minutes or more without additional fuel being added; and the system can be configured to expel substantially no reaction products outside of the system (e.g., into the environment).
The system further optionally comprises a controller that, upon sensing the occurrence of a power outage condition, operatively engages the one or more metal fuel cells and/or engages a flow of the one or more second reactants at a time prior to in the range(s) from about 10 microseconds to about 10 seconds after the controller senses the occurrence of a power outage condition. Optionally, the controller can be configured to sense a cessation of the power outage condition and, responsive thereto, to engage the primary power to provide power to one or more of the optional regeneration units in the one or more fuel cells and/or to disengage the one or more fuel cells from providing power to the one or more loads. The system can also optionally further comprise a power converter to convert to alternating current (AC), or to another form of direct current (DC), the DC power output by the one or more fuel cells.
The system further comprises a cooling unit that is powered by the one or more fuel cells upon the occurrence of a power outage condition. This cooling unit is configured to remove from the vicinity of the system heat generated by the one or more loads and/or the one or more fuel cells.
In one embodiment, the cooling unit is configured to blow cool fluid (for example and without limitation, gas (e.g., air), liquid (e.g., liquid coolant), and the like, and suitable combinations thereof) past the one or more fuel cells and/or the one or more loads. In a second embodiment, the cooling unit is an open loop system configured to cool a first cooling fluid (e.g., air) by circulating a second cooling fluid (e.g., liquid coolant) through a heat exchanger. The first cooling fluid is then blown past the one or more fuel cells and/or the one or more loads. In a third embodiment, the cooling unit is a closed loop system configured to cool a first cooling fluid (e.g., air) by circulating a second cooling fluid (e.g., liquid coolant) from a reservoir (not in the immediate vicinity of the system) through a heat exchanger and then back to the reservoir. The first cooling fluid is then blown past the one or more fuel cells and/or the one or more loads.
In one implementation, the system of the invention further optionally comprises means for physically supporting the one or more fuel cells, and at least one of the one or more loads, and/or means for routing a cooling fluid, whether gas, liquid, or both gas and liquid, past the one or more fuel cells and/or the one or more loads. Optionally, the means for supporting can be configured to support one or more of the remainder of the one or more loads, the controller, and/or the optional power conversion stage.
Each of these two means, as well as each of the other components of the system, can be separate from, or integral with, one or more of the other components of the system.
In another embodiment, the invention provides a method of providing backup power to one or more loads and to a cooling unit.
In addition, the invention provides methods of providing backup power to one or more loads (including without limitation a cooling unit) comprising, upon sensing an outage of primary power to the one or more loads, operatively engaging one or more metal fuel cells to provide power to the one or more loads. The invention also provides methods of pre-charging a fuel cell system for providing backup power to one or more loads (including without limitation a cooling unit) comprising placing an amount of fuel in cell cavities of a power source of a fuel cell system prior to operative engagement of the fuel cell system. The invention further provides methods of utilizing a pre-charged fuel cell system for providing backup power to one or more loads (including without limitation a cooling unit), comprising operatively engaging a fuel cell system containing fuel in cell cavities of a power source of the fuel cell system prior to its operative engagement for a time in the range from about 0.001 minutes to about 100 minutes without adding additional fuel thereto.
Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims.